how to count # rows having overlapping date ranges

I've attached a spreadsheet to illustrate the question.

It shows various trades, including opening and closing times.

Some trades "overlap" others.

For any particular row, in column C, I need to count how many other trades are open at the same time.

It seems like it should be a simple formula but I'm not having success either with COUNTIF or SUMIFS.

thanks in advance for the help!

I've taken a look at your workbook and i'm still not wiser, i cannot fathom out what you are trying to acheive or where you are checking for overlaps...etc

I hope this will help:

1. This is a spreadsheet of currency trades.

2. Each trade opens at a certain time/date (column J) and closes at a certain time/date (column L). (note the date formats are US, not UK).

3. The spreadsheet is sorted by column L, in ascending order.

4. You will notice that some trades last longer than others. As a consequence, there are times when more than one trade is open.

5. For the example I refer to in the spreadsheet (the trade on row 5) you will see that it opened on 9/30/2009 21:00, and closed on 10/01/2009 at 13:10. Let's call that "date range 5"

6. The task now is to see if any other trades were open during "date range 5."

7. If we look at rows 3 and 4 we see that both of them were open at some point during "date range 5." (they opened later than 5, but 5 remained open during part of time that 5 was still open). Thus the date ranges "overlapped."

8. The formula I need should "count" rows 3,4 and 5, giving a solution of "3."

It seems to me that the formula would need to be a SUMIFS and include MAX/MIN calcs. But how to write it... is beyond me!
Thanks much.